The invention relates to consolidating or strengthening unconsolidated or poorly consolidated subterranean reservoir formations, and/or sand or gravel packs within the borehole of a well, and/or masses of propping particles within hydraulically induced fractures, or the like, within subterranean earth formations.
In various aspects the present invention involves an improvement of a process of the type described in the I. H. Havenaar and F. H. Meijs U.S. Pat. No. 3,294,166 or the F. H. Meijs U.S. Pat. No. 4,113,015. Said 166 patent describes sand consolidations using an epoxy resin-forming solution which contains polyepoxides and polyamino curing agents. That solution contains a ratio of aromatic and aliphatic hydrocarbons which causes it to dissolve those reactants and, without gelation, to precipitate a partially cured epoxy resin which subsequently becomes completely cured. The 015 patent describes a similar process in which the viscosity of such a resin-forming solution is increased by the presence of an otherwise substantially inert oil-soluble polymer. The disclosures of the U.S. Pat. Nos. 3,294,166 and 4,113,015 are incorporated herein by cross reference.
In other aspects, the present invention involves an improvement of a process of the type described in the E. A. Richardson U.S. Pat. No. 3,339,633. The 633 patent describes sand consolidations using an epoxy resin forming solution which contains a polyepoxides and polyamino curing agents and partially cured epoxy resins dissolved in a polar organic group-containing solvent in which they remain dissolved until the polar solvent is contacted by an overflushing portion of predominantly aliphatic hydrocarbon oil solvent that induces the precipitation of a selected proportion of resin on the particles of the sand being consolidated. The disclosures U.S. of Pat. No. 3,339,633 are incorporated herein by cross-reference.
Dimethylaminomethyl-substituted phenols have previously been used in epoxy resin-forming solutions. They are useful as phenolic-type curing rate accelerators, for example, as described in the 166 and 015 patents or the U.S. Pat. No. 3,933,204 by R. H. Knapp and S. G. Almquist. In the latter patent, the resin curing reaction which is accelerated is that between an epoxy-resin-forming epoxide and an acrylic-resin-forming polycarboxide within resin-forming solutions which are adapted for plugging relatively permeable subterranean earth formations.
A different use for the dimethylaminomethyl-substituted phenols is described in the R. H. Knapp U.S. Pat. No. 4,000,781. It describes well treating processes for consolidated particles with aqueous emulsions of epoxy-resin-forming components. In such emulsions such phenols are used as substantially the only curing agent and are dissolved in an epoxide-containing oil solvent which is emulsified within an aqueous liquid. In the process of the 781 patent, the dimethylaminomethyl-substituted phenol functions as both a curing agent and a wetting agent. The surfaces of the particles to be consolidated are coated with the resin-forming solution by controlling the pH of the emulsion so that it breaks while it is in contact with those surfaces.